A media gateway (MG) is a network node straddling two network domains and mediating between two different networks while providing media level physical resources appropriate to a specific connected network. Typically, media gateways are situated between a public switched telephone network (PSTN) network and an Internet protocol (IP) network. When a connection requiring MG services is made, such as a voice over IP (VOIP) call, MGs may communicate with other MGs over an IP network. Often, MGs are connected together by multiple routes in an IP communications network. A conventional MG uses destination-based IP routing tables and destination-based routing algorithms to route IP packets to other MGs. For example, the routing table in a conventional MG includes an entry containing routing information associated with each destination. Thus, all packets addressed to a particular MG are routed via the route defined in the destination-based routing table entry corresponding to that destination.
Additionally, conventional media gateways typically route packets based on data flows, such as a transmission control protocol (TCP) or user datagram protocol (UDP) sessions. Packets belonging to the same data flow as those previously transmitted are transmitted to the destination via the same route as the previously transmitted packets in the data flow. Because the route used to transmit a packet may depend on the route used to route a previous packet, the destination node must initially transmit one or more packets before subsequent dataflow-based packet forwarding may be used.
One problem associated with data flow based packet forwarding used in conventional media gateways is that complex logic is required to process data flow packets. This additional complexity increases the cost and transmission delay for packets routed at a MG using conventional routing methods.
Another problem associated with destination-based IP routing used in conventional MGs is an inability to route packets over multiple routes to a single destination. Because destination-based IP routing tables associate a single destination with a single route, all packets addressed to a particular destination address are transmitted over only one of the available routes.
Yet another problem associated with destination-based IP routing in conventional MGs is an inability to load-balance IP traffic between MGs connected by multiple routes. For example, a conventional MG routing table contains one entry for each destination address, where each entry contains information associated with a route to the destination. For example, packets addressed to a first destination may be routed via a first outgoing interface and a first nexthop address. Therefore, if two MGs are connected by multiple outgoing interfaces and multiple nexthop addresses, the routing tables for each conventional MG specifies only one route, not multiple routes. As the number of IP packets transmitted between MGs increases, the importance of load-balancing IP traffic over multiple routes between MGs grows.
Accordingly, a need exists for improved methods and systems for load-balancing IP traffic between media gateways connected by multiple routes.